Acute renal colic Radiological investigation in patients with renal colic

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1 Acute renal colic Radiological investigation in patients with renal colic Mikael Hellström Professor Department of Radiology Sahlgrenska University Hospital Göteborg University /1.000 inhabitants and year Average age ~40 years Recurrence of upper urinary stone disease within 10 years: 40-50% (Ljunghall 1977, Ahlstrand et al 1981) Critical issues Obstruction must be detected and treated Increased intrarenal pressure due to ureteric obstruction may lead to impaired function and parenchymal damage Restitution of renal function is possible if obstruction is relieved within 2 weeks Obstruction + infection shortens this interval and may lead to uro-sepsis Spontaneous stone passage (based on size at CT) Transv diam 4 mm: 78% spontaneous stone passage Trans diam 5-7 mm: 60% spontaneous stone passage 8 mm: 39% 10 mm: 0% Coll et al, AJR 2002;178:101 ~75% of all stones pass spontaneously Likelihood of passage of ureteral stones Stone size <2 mm 3 mm Mean time to pass stone (days) 8 12 Likelihood of eventual need for intervention (%) 3 14 Acute renal colic Do we need acute imaging in all patients? 4-6 mm >6 mm Teichman, NEJM 2004;350:

2 Acute flank pain EAU Guidelines Sweden The clinical diagnosis should be supported by an appropriate imaging procedure. Guidelines on Urolithiasis European Association of Urology (EAU) 2006 Acute imaging Elective imaging (2-3 w) Uncertain diagnosis Fever Single kidney Analgetics ineffective All others ~75% of all stones pass spontaneously If we do imaging acutely on all patients we will detect all stones, before spontaneous stone passage occurs Once detected, a ureteric stone has to be checked with f/u imaging in every patient to ensure stone passage Thus, such a strategy leads to at least 2 imaging procedures in every patient with stone In only a minority (~1/4) of patients with renal colic, acute imaging is absolutely mandatory - intractable pain - fever - single kidney - unclear diagnosis In the rest of the patients, imaging can be deferred and a large proportion of patients will be spared a second imaging, since their stone has passed in 75% of the cases at the time of imaging (2-3 weeks) Acute renal colic Acute or deferred imaging? What difference does it make? Acute or deferred imaging? Prospective, randomized study Acute renal colic, suspected stone disease Attending Sahlgrenska University Hospital Patients who became pain free after 2 or 3 iv injections of analgetics Excluded: Fever, not pain-free on treatment, single kidney or unclear clinical diagnosis (acute imaging) 172 patients randomised Acute imaging or deferred imaging K.Lindqvist, M.Hellström, G.Holmberg R. Peeker, L.Grenabo Scand J Urol Nephrol

3 Patients attending the Emergency Departments at Sahlgrenska University Hospital for acute renal colic Randomised within 24 hours after start of symptoms N=172 Results Morbidity and diagnostic timing Structured, self-assessed questionnaire, 4 weeks daily reporting Acute imaging Imaging after 2-3 w n=78 n=72 Impaired daily activities, days 3.6 (2/0-25) 3.4 (2/0-19) N.S. Consumption of analgetics, days 4.8 (2/0-38) 3.6 (2/0-20) N.S. Acute Imaging (within 24 h) N=86 Deferred Imaging (after 2-3 weeks) N=86 K.Lindqvist, M.Hellström, G.Holmberg R. Peeker, L.Grenabo Scand J Urol Nephrol 2006 Acute medical consultation, pat 11 (14)% 11 (15%) N.S. Acute hospital admission, pat 3 (4%) 5 (7%) N.S. Interventional procedure 13 (17%) 6 (8%) N.S. Frequency of stones 70% 39% K.Lindqvist, M.Hellström, G.Holmberg R. Peeker, L.Grenabo Scand J Urol Nephrol 2006 Timing of imaging What do we want to know? Acute imaging Elective imaging (2 w) Uncertain diagnosis Fever Single kidney Analgetics ineffective All others Number of stones Size Shape Position Renal function Degree of obstruction Acute flank pain, suspected stone disease Urography Computed tomography (CT) (Ultrasonography) (MRI) Ultrasonography Dilatation + stone BC 3

4 Ultrasonography Stone in renal pelvis, most proximal or most distal parts of ureter can be demonstrated, but. Small stones in pelvicalyceal system are easily missed Stones in the midureter are easily missed Renal function can not be assessed Observer dependent Patient dependent Image documentation insufficient Ultrasonography however In pregnant women and very young patients, ultrasound in combination with plain film (KUB) can be an alternative Ultrasonography is insufficient as primary method for assessment of stone disease Comparison of same-day non-enhanced CT vs Ultrasonongraphy + plain radiography MRI N=160 CT Plain +US Confirmed stone in ureter, n=82 Sensitivity 79/82 (96%) 62/82 (76%) Heavily T2-weighted MRI (static MRU) Gd-enhanced T1-weighted MRI (dynamic MRU) Insufficient for detection of calcifications (stones) Limited availability for acute imaging Expensive Catalano et al, AJR 2002;178: MRI is insufficient as primary method for assessment of stone disease Acute flank pain Do we need urography any more? Urography - assessment of acute flank pain - Advantages Time-honoured Osborne et al. JAMA 1923;80(6) Good demonstration of pelvicalyceal system and ureter Detects most stones Allows evaluation of renal function and obstruction 4

5 Urography reveals very discrete outflow obstruction Urography - acute flank pain - Disadvantages iv contrast Stones may be missed obscuring structures (sacrum, bowel) small stones non-opaque stones adipose patient misinterpretation (phleboliths) Takes time if excretion is delayed Abnormalities outside urinary tract not identified LL c 5

6 Right flank pain 10 min XX a Stone? XX b Delayed excretion 20 min 40 min XX c Delayed excretion XX d Delayed excretion Excretion after 2 hours, but level of obstruction still not confirmed additional delayed imaging to follow XX e 120 min Non-enhanced CT - advantages vs urography - No iv contrast needed no hypersensitivity problems no adverse effects on renal function Faster MDCT: scan time <20 sec, room time <15 minutes Urography: 20 min - hours Virtually all stones (including non-opaque stones) can be identified at CT - exception: Indinavir-concrements (HIVtreatment) Detection of abnormalities outside urinary tract possible 6

7 Non-enhanced CT MDCT from kidneys to symphysis No iv or oral contrast Avoid micturition before scanning Narrow collimation e.g. 8x2.5 mm; 16x0.6 mm Cine viewing (follow ureter) Variable window settings (perirenal fatty tissue) Reduced radiation (lower mas) Nonenhanced-CT for renal colic (Smith et al AJR 1996) 100 patients with acute flank pain CT + urography + follow-up Sensitivity 97% Specificity 96% Accuracy 97% Other diagnoses in 31 patients Nonenhanced-CT in acute flank pain Visible calcification (stone) in ureter Hydroureter/hydronephrosis Perinephric/periureteric stranding Local ureteric edema around stone (tissue rim sign) Enlargedkidney Reduced density (HU) on affected side 5 HU difference: 61% sens; 100% spec; (Goldman et al, AJR 2004) Post ESWL LE LE LE 7

8 LE LE Incidental findings Advantage or disadvantage? LE LE Calcification (stone) in ureter Edema (tissue rim sign) 8

9 August 10 August 10 Right flank pain Right flank pain Minimal reaction around kidney Tissue rim sign No hydronephrosis FF 1a FF 1b September 20 September 20 New episode of acute flank pain Perinehric stranding Perinehric stranding) Hydronephrosis FF 2a FF 2b Signs of obstruction! September 20 September 20 Hydroureter Hydronephrosis FF 2c FF 2d 9

10 September 20 September 20 FF 2e FF 2f September 20 September 20 FF 2g FF 2h September 20 September 20 Stone + edema (tissue rim sign) FF 2i FF 2j 10

11 September 20 Effects of hydronephrosis August 10 September 20 FF 2k Fullness of renal pelvis Compression of sinus fat Perinephric stranding Perinephric stranding and fluid KZ KZ Left flank pain Left flank pain LT 66 y LT 66 y 11

12 Hydronephrosis 1 hour Level of obstruction? 1 hour LT 66 y LT 66 y Hydroureter, 8 mm LT 66 y LT 66 y 4 mm stone in distal ureter CT shows small stones not seen by urography 2.5 mm LT 66 y 12

13 Right flank pain Non-enhanced CT in flank pain Pitfalls Stone, in vesicoureteral junction or in bladder? R.I. e Right flank pain Opposite body position to determine stone location R.I. f Supine Prone Nonenhanced-CT in flank pain Pitfalls distal ureteric stone vs phleboliths No direct information on renal function Lack of hydroureter/hydronephrosis Little retroperitoneal fatty tissue Phleboliths Calcifications in pelvic veins Normal phenomenon Increase with age No sex preponderance May simulate ureteral stone Radiolucent centre on plain film 13

14 Phleboliths vs stones Phleboliths Radiolucent center Phlebolith vs stone (Traubici et al AJR 1999;172:13-17) 120 phleboliths in 50 patients with flank pain urography: 79/120 (66%) radiolucent centre CT: 1/120 (<1%) radiolucent centre Minimal retroperitoneal fat Perinephric stranding?? Radiolucent centre not useful for CT differentiation of stone vs phlebolith Where is the ureter?? Easy Pitfalls nonenhanced CT Obstruction does not always cause dilatation early obstruction (hours) reduced renal function, low filtration pressure calyceal (fornix) rupture may cause decompression Pitfalls non-enhanced CT Dilatation does not always mean obstruction Dilatation may persist after correction of obstruction 14

15 Varanelli, M. J. et al. Am. J. Roentgenol. 2001;177: Copyright 2007 by the American Roentgen Ray Society Copyright 2007 by the American Roentgen Ray Society Varanelli, M. J. et al. Am. J. Roentgenol. 2001;177: Copyright 2007 by the American Roentgen Ray Society Varanelli, M. J. et al. Am. J. Roentgenol. 2001;177: Copyright 2007 by the American Roentgen Ray Society Varanelli, M. J. et al. Am. J. Roentgenol. 2001;177: Copyright 2007 by the American Roentgen Ray Society Copyright 2007 by the American Roentgen Ray Society Varanelli, M. J. et al. Am. J. Roentgenol. 2001;177: Copyright 2007 by the American Roentgen Ray Society Varanelli, M. J. et al. Am. J. Roentgenol. 2001;177: Impact of duration of pain? --Line graph shows frequency of ureteral dilatation as function of duration of pain --Line graph shows frequency of collecting system dilatation as function of duration of pain Varanelli et al, AJR 2001 Prospective 227 consecutive patients with acute ureterolithisasis on non-enhanced CT mas at 120 kv Duration of pain registered Varanelli et al AJR Line graph shows frequency of moderate or severe perinephric stranding as function of duration --Line graph shows frequency of moderate or severe perinephric fluid as function of duration of pain of pain --Line graph shows frequency of periureteral stranding as function of duration of pain --Line graph shows frequency of ureteral rim sign as function of duration of pain Impact of duration of pain --Line graph shows frequency of nephromegaly as function of duration of pain Varanelli et al AJR 2001 Perinephric stranding Any degree of stranding was seen in 72-79% of all patients Of those with 2 hours pain duration, 5% had moderate or severe stranding, compared to 51% in those with 7-8 hours pain duration Varanelli et al AJR 2001 Varanelli, M. J. et al. Am. J. Roentgenol. 2001;177: y Time of occurrence of pain (e.g ) should be stated on the request form for patients with acute renal colic! Right flank pain, suspected ureteric stone No stone detected KA 15

16 60 y 9 min Right flank pain, suspected ureteric stone 60-y Susp Right renal colic KA KA What about the radiation dose? Intravenous contrast series should be added if diagnosis is in doubt Stone-CT can be performed with low dose radiation Poletti et al AJR April 2007: 125 patients with renal coloic 30 mas mas MDCT same day 42 y old man with right flank pain 42 y old man with right flank pain 30 mas 180 mas Poletti et al AJR 2007;188: mas 180 mas Stone size underestimated Poletti et al AJR 2007;188:

17 43 year old over-weight BMI = 30 Intense left flank pain and hematuria 43 year old over-weight BMI = 30 Intense left flank pain and hematuria Stone?? 4.5 mm stone 30 mas Poletti et al AJR 2007;188: mas 180 mas Poletti et al AJR 2007;188: Poletti et al, AJR April 2007 N=125 patients with renal colic 30 mas BMI<30 30 mas BMI>30 30 mas All pat N=125 patients with renal colic 30 mas 180 mas Calculi Sensitivity Calculi Specificity 95% (77/81) 97% (30/31) 50% (2/4) 89% (8/9) 93% (79/85) 95% (38/40) Men 1.6 ±0.2 msv 9.6 ±1.2 msv Indirect signs Sensitivity 96% (84/87) 100% (7/7) 98% (91/93) Women 2.1 ±0.3 msv 12.6 ±1.8 msv Indirect signs Specificity 100% (26/26) 100% (6/6) 100% (32/32) Poletti et al AJR 2007;188: mas as reference standard N=121 patients with renal colic Men (mean) Women (mean) 50 mas 1.4 msv 2.0 msv 260 mas 7.3 msv 10.0 msv Low-dose CT Low-dose CT (30 mas) did not miss any calculus 3 mm in patients with BMI <30 Smaller calculi (<3 mm) may be missed (83% sensitivity) Exact stone size measurements less reliable, may vary by ±20% Kim et al Acta Radiol 2005;46:

18 Remember Add intravenous contrast when in doubt! Thank you 18